MSM84 Labrador Glacials

Summary – MSM84 June 18th to July 17th, 2019 St. John’s (Canada) – St. John’s (Canada)

The Labrador shelf, located off the eastern Canadian coast, is a key area for paleoclimate and paleoceanographic research. The Canadian hinterland was covered by the Laurentide Ice Sheet during glacials. During phases of ice melt at the transition from glacials to interglacials, large amounts of fresh water were released into the Labrador Sea and North Atlantic Ocean. This release of fresh water occurred through fjords and adjacent troughs Mehr that were excavated by ice streams during the glacials. In addition, these fresh water pulses have a profound influence on the strength of the Atlantic meridional overturning circulation, which in turn significantly influences the climate of the Northern Hemisphere.

Our seismic source in front of an iceberg (picture by F. Gross).

So far, the dynamics of the Laurentide Ice Sheet were reconstructed based on marine sediment cores that were taken mostly far offshore from the North Atlantic. This area was never directly covered by the Laurentide Ice Sheet. Direct evidence from glacial features on the shelf was largely missing. Therefore, the goal of expedition MSM84 was the investigation of the glacial history of the Labrador shelf and hence the glacial history of the eastern part of the Laurentide Ice Sheet. In addition to the Labrador shelf area, Lake Melville, a small inlet into the eastern Canadian coast was investigated.

During the expedition different geophysical and geological methods were used by the scientific party from University of Kiel, Alfred-Wegener-Institute Bremerhaven, University of Bremen, Université Laval and Université du Québec à Montreal et à Rimouski. The seafloor and the deeper sedimentary layers of the Labrador shelf and Lake Melville were imaged with hydro- and geoacoustic methods (bathymetry, parasound, 2D high-resolution seismic). Additionally, interesting features were sampled with a gravity corer, multi corer and box corer.